/* * POSIX message queues filesystem for Linux. * * Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl) * Michal Wronski (michal.wronski@gmail.com) * * Spinlocks: Mohamed Abbas (abbas.mohamed@intel.com) * Lockless receive & send, fd based notify: * Manfred Spraul (manfred@colorfullife.com) * * Audit: George Wilson (ltcgcw@us.ibm.com) * * This file is released under the GPL. */ #include <linux/capability.h> #include <linux/init.h> #include <linux/pagemap.h> #include <linux/file.h> #include <linux/mount.h> #include <linux/namei.h> #include <linux/sysctl.h> #include <linux/poll.h> #include <linux/mqueue.h> #include <linux/msg.h> #include <linux/skbuff.h> #include <linux/vmalloc.h> #include <linux/netlink.h> #include <linux/syscalls.h> #include <linux/audit.h> #include <linux/signal.h> #include <linux/mutex.h> #include <linux/nsproxy.h> #include <linux/pid.h> #include <linux/ipc_namespace.h> #include <linux/user_namespace.h> #include <linux/slab.h> #include <linux/sched/wake_q.h> #include <linux/sched/signal.h> #include <linux/sched/user.h> #include <net/sock.h> #include "util.h" #define MQUEUE_MAGIC 0x19800202 #define DIRENT_SIZE 20 #define FILENT_SIZE 80 #define SEND 0 #define RECV 1 #define STATE_NONE 0 #define STATE_READY 1 struct posix_msg_tree_node { struct rb_node rb_node; struct list_head msg_list; int priority; }; struct ext_wait_queue { /* queue of sleeping tasks */ struct task_struct *task; struct list_head list; struct msg_msg *msg; /* ptr of loaded message */ int state; /* one of STATE_* values */ }; struct mqueue_inode_info { spinlock_t lock; struct inode vfs_inode; wait_queue_head_t wait_q; struct rb_root msg_tree; struct posix_msg_tree_node *node_cache; struct mq_attr attr; struct sigevent notify; struct pid *notify_owner; struct user_namespace *notify_user_ns; struct user_struct *user; /* user who created, for accounting */ struct sock *notify_sock; struct sk_buff *notify_cookie; /* for tasks waiting for free space and messages, respectively */ struct ext_wait_queue e_wait_q[2]; unsigned long qsize; /* size of queue in memory (sum of all msgs) */ }; static const struct inode_operations mqueue_dir_inode_operations; static const struct file_operations mqueue_file_operations; static const struct super_operations mqueue_super_ops; static void remove_notification(struct mqueue_inode_info *info); static struct kmem_cache *mqueue_inode_cachep; static struct ctl_table_header *mq_sysctl_table; static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode) { return container_of(inode, struct mqueue_inode_info, vfs_inode); } /* * This routine should be called with the mq_lock held. */ static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode) { return get_ipc_ns(inode->i_sb->s_fs_info); } static struct ipc_namespace *get_ns_from_inode(struct inode *inode) { struct ipc_namespace *ns; spin_lock(&mq_lock); ns = __get_ns_from_inode(inode); spin_unlock(&mq_lock); return ns; } /* Auxiliary functions to manipulate messages' list */ static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info) { struct rb_node **p, *parent = NULL; struct posix_msg_tree_node *leaf; p = &info->msg_tree.rb_node; while (*p) { parent = *p; leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node); if (likely(leaf->priority == msg->m_type)) goto insert_msg; else if (msg->m_type < leaf->priority) p = &(*p)->rb_left; else p = &(*p)->rb_right; } if (info->node_cache) { leaf = info->node_cache; info->node_cache = NULL; } else { leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC); if (!leaf) return -ENOMEM; INIT_LIST_HEAD(&leaf->msg_list); } leaf->priority = msg->m_type; rb_link_node(&leaf->rb_node, parent, p); rb_insert_color(&leaf->rb_node, &info->msg_tree); insert_msg: info->attr.mq_curmsgs++; info->qsize += msg->m_ts; list_add_tail(&msg->m_list, &leaf->msg_list); return 0; } static inline struct msg_msg *msg_get(struct mqueue_inode_info *info) { struct rb_node **p, *parent = NULL; struct posix_msg_tree_node *leaf; struct msg_msg *msg; try_again: p = &info->msg_tree.rb_node; while (*p) { parent = *p; /* * During insert, low priorities go to the left and high to the * right. On receive, we want the highest priorities first, so * walk all the way to the right. */ p = &(*p)->rb_right; } if (!parent) { if (info->attr.mq_curmsgs) { pr_warn_once("Inconsistency in POSIX message queue, " "no tree element, but supposedly messages " "should exist!\n"); info->attr.mq_curmsgs = 0; } return NULL; } leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node); if (unlikely(list_empty(&leaf->msg_list))) { pr_warn_once("Inconsistency in POSIX message queue, " "empty leaf node but we haven't implemented " "lazy leaf delete!\n"); rb_erase(&leaf->rb_node, &info->msg_tree); if (info->node_cache) { kfree(leaf); } else { info->node_cache = leaf; } goto try_again; } else { msg = list_first_entry(&leaf->msg_list, struct msg_msg, m_list); list_del(&msg->m_list); if (list_empty(&leaf->msg_list)) { rb_erase(&leaf->rb_node, &info->msg_tree); if (info->node_cache) { kfree(leaf); } else { info->node_cache = leaf; } } } info->attr.mq_curmsgs--; info->qsize -= msg->m_ts; return msg; } static struct inode *mqueue_get_inode(struct super_block *sb, struct ipc_namespace *ipc_ns, umode_t mode, struct mq_attr *attr) { struct user_struct *u = current_user(); struct inode *inode; int ret = -ENOMEM; inode = new_inode(sb); if (!inode) goto err; inode->i_ino = get_next_ino(); inode->i_mode = mode; inode->i_uid = current_fsuid(); inode->i_gid = current_fsgid(); inode->i_mtime = inode->i_ctime = inode->i_atime = current_time(inode); if (S_ISREG(mode)) { struct mqueue_inode_info *info; unsigned long mq_bytes, mq_treesize; inode->i_fop = &mqueue_file_operations; inode->i_size = FILENT_SIZE; /* mqueue specific info */ info = MQUEUE_I(inode); spin_lock_init(&info->lock); init_waitqueue_head(&info->wait_q); INIT_LIST_HEAD(&info->e_wait_q[0].list); INIT_LIST_HEAD(&info->e_wait_q[1].list); info->notify_owner = NULL; info->notify_user_ns = NULL; info->qsize = 0; info->user = NULL; /* set when all is ok */ info->msg_tree = RB_ROOT; info->node_cache = NULL; memset(&info->attr, 0, sizeof(info->attr)); info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max, ipc_ns->mq_msg_default); info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max, ipc_ns->mq_msgsize_default); if (attr) { info->attr.mq_maxmsg = attr->mq_maxmsg; info->attr.mq_msgsize = attr->mq_msgsize; } /* * We used to allocate a static array of pointers and account * the size of that array as well as one msg_msg struct per * possible message into the queue size. That's no longer * accurate as the queue is now an rbtree and will grow and * shrink depending on usage patterns. We can, however, still * account one msg_msg struct per message, but the nodes are * allocated depending on priority usage, and most programs * only use one, or a handful, of priorities. However, since * this is pinned memory, we need to assume worst case, so * that means the min(mq_maxmsg, max_priorities) * struct * posix_msg_tree_node. */ mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) + min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) * sizeof(struct posix_msg_tree_node); mq_bytes = mq_treesize + (info->attr.mq_maxmsg * info->attr.mq_msgsize); spin_lock(&mq_lock); if (u->mq_bytes + mq_bytes < u->mq_bytes || u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) { spin_unlock(&mq_lock); /* mqueue_evict_inode() releases info->messages */ ret = -EMFILE; goto out_inode; } u->mq_bytes += mq_bytes; spin_unlock(&mq_lock); /* all is ok */ info->user = get_uid(u); } else if (S_ISDIR(mode)) { inc_nlink(inode); /* Some things misbehave if size == 0 on a directory */ inode->i_size = 2 * DIRENT_SIZE; inode->i_op = &mqueue_dir_inode_operations; inode->i_fop = &simple_dir_operations; } return inode; out_inode: iput(inode); err: return ERR_PTR(ret); } static int mqueue_fill_super(struct super_block *sb, void *data, int silent) { struct inode *inode; struct ipc_namespace *ns = sb->s_fs_info; sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV; sb->s_blocksize = PAGE_SIZE; sb->s_blocksize_bits = PAGE_SHIFT; sb->s_magic = MQUEUE_MAGIC; sb->s_op = &mqueue_super_ops; inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL); if (IS_ERR(inode)) return PTR_ERR(inode); sb->s_root = d_make_root(inode); if (!sb->s_root) return -ENOMEM; return 0; } static struct dentry *mqueue_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { struct ipc_namespace *ns; if (flags & MS_KERNMOUNT) { ns = data; data = NULL; } else { ns = current->nsproxy->ipc_ns; } return mount_ns(fs_type, flags, data, ns, ns->user_ns, mqueue_fill_super); } static void init_once(void *foo) { struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo; inode_init_once(&p->vfs_inode); } static struct inode *mqueue_alloc_inode(struct super_block *sb) { struct mqueue_inode_info *ei; ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL); if (!ei) return NULL; return &ei->vfs_inode; } static void mqueue_i_callback(struct rcu_head *head) { struct inode *inode = container_of(head, struct inode, i_rcu); kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode)); } static void mqueue_destroy_inode(struct inode *inode) { call_rcu(&inode->i_rcu, mqueue_i_callback); } static void mqueue_evict_inode(struct inode *inode) { struct mqueue_inode_info *info; struct user_struct *user; unsigned long mq_bytes, mq_treesize; struct ipc_namespace *ipc_ns; struct msg_msg *msg; clear_inode(inode); if (S_ISDIR(inode->i_mode)) return; ipc_ns = get_ns_from_inode(inode); info = MQUEUE_I(inode); spin_lock(&info->lock); while ((msg = msg_get(info)) != NULL) free_msg(msg); kfree(info->node_cache); spin_unlock(&info->lock); /* Total amount of bytes accounted for the mqueue */ mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) + min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) * sizeof(struct posix_msg_tree_node); mq_bytes = mq_treesize + (info->attr.mq_maxmsg * info->attr.mq_msgsize); user = info->user; if (user) { spin_lock(&mq_lock); user->mq_bytes -= mq_bytes; /* * get_ns_from_inode() ensures that the * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns * to which we now hold a reference, or it is NULL. * We can't put it here under mq_lock, though. */ if (ipc_ns) ipc_ns->mq_queues_count--; spin_unlock(&mq_lock); free_uid(user); } if (ipc_ns) put_ipc_ns(ipc_ns); } static int mqueue_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool excl) { struct inode *inode; struct mq_attr *attr = dentry->d_fsdata; int error; struct ipc_namespace *ipc_ns; spin_lock(&mq_lock); ipc_ns = __get_ns_from_inode(dir); if (!ipc_ns) { error = -EACCES; goto out_unlock; } if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max && !capable(CAP_SYS_RESOURCE)) { error = -ENOSPC; goto out_unlock; } ipc_ns->mq_queues_count++; spin_unlock(&mq_lock); inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr); if (IS_ERR(inode)) { error = PTR_ERR(inode); spin_lock(&mq_lock); ipc_ns->mq_queues_count--; goto out_unlock; } put_ipc_ns(ipc_ns); dir->i_size += DIRENT_SIZE; dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(dir); d_instantiate(dentry, inode); dget(dentry); return 0; out_unlock: spin_unlock(&mq_lock); if (ipc_ns) put_ipc_ns(ipc_ns); return error; } static int mqueue_unlink(struct inode *dir, struct dentry *dentry) { struct inode *inode = d_inode(dentry); dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(dir); dir->i_size -= DIRENT_SIZE; drop_nlink(inode); dput(dentry); return 0; } /* * This is routine for system read from queue file. * To avoid mess with doing here some sort of mq_receive we allow * to read only queue size & notification info (the only values * that are interesting from user point of view and aren't accessible * through std routines) */ static ssize_t mqueue_read_file(struct file *filp, char __user *u_data, size_t count, loff_t *off) { struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp)); char buffer[FILENT_SIZE]; ssize_t ret; spin_lock(&info->lock); snprintf(buffer, sizeof(buffer), "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n", info->qsize, info->notify_owner ? info->notify.sigev_notify : 0, (info->notify_owner && info->notify.sigev_notify == SIGEV_SIGNAL) ? info->notify.sigev_signo : 0, pid_vnr(info->notify_owner)); spin_unlock(&info->lock); buffer[sizeof(buffer)-1] = '\0'; ret = simple_read_from_buffer(u_data, count, off, buffer, strlen(buffer)); if (ret <= 0) return ret; file_inode(filp)->i_atime = file_inode(filp)->i_ctime = current_time(file_inode(filp)); return ret; } static int mqueue_flush_file(struct file *filp, fl_owner_t id) { struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp)); spin_lock(&info->lock); if (task_tgid(current) == info->notify_owner) remove_notification(info); spin_unlock(&info->lock); return 0; } static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab) { struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp)); int retval = 0; poll_wait(filp, &info->wait_q, poll_tab); spin_lock(&info->lock); if (info->attr.mq_curmsgs) retval = POLLIN | POLLRDNORM; if (info->attr.mq_curmsgs < info->attr.mq_maxmsg) retval |= POLLOUT | POLLWRNORM; spin_unlock(&info->lock); return retval; } /* Adds current to info->e_wait_q[sr] before element with smaller prio */ static void wq_add(struct mqueue_inode_info *info, int sr, struct ext_wait_queue *ewp) { struct ext_wait_queue *walk; ewp->task = current; list_for_each_entry(walk, &info->e_wait_q[sr].list, list) { if (walk->task->static_prio <= current->static_prio) { list_add_tail(&ewp->list, &walk->list); return; } } list_add_tail(&ewp->list, &info->e_wait_q[sr].list); } /* * Puts current task to sleep. Caller must hold queue lock. After return * lock isn't held. * sr: SEND or RECV */ static int wq_sleep(struct mqueue_inode_info *info, int sr, ktime_t *timeout, struct ext_wait_queue *ewp) __releases(&info->lock) { int retval; signed long time; wq_add(info, sr, ewp); for (;;) { __set_current_state(TASK_INTERRUPTIBLE); spin_unlock(&info->lock); time = schedule_hrtimeout_range_clock(timeout, 0, HRTIMER_MODE_ABS, CLOCK_REALTIME); if (ewp->state == STATE_READY) { retval = 0; goto out; } spin_lock(&info->lock); if (ewp->state == STATE_READY) { retval = 0; goto out_unlock; } if (signal_pending(current)) { retval = -ERESTARTSYS; break; } if (time == 0) { retval = -ETIMEDOUT; break; } } list_del(&ewp->list); out_unlock: spin_unlock(&info->lock); out: return retval; } /* * Returns waiting task that should be serviced first or NULL if none exists */ static struct ext_wait_queue *wq_get_first_waiter( struct mqueue_inode_info *info, int sr) { struct list_head *ptr; ptr = info->e_wait_q[sr].list.prev; if (ptr == &info->e_wait_q[sr].list) return NULL; return list_entry(ptr, struct ext_wait_queue, list); } static inline void set_cookie(struct sk_buff *skb, char code) { ((char *)skb->data)[NOTIFY_COOKIE_LEN-1] = code; } /* * The next function is only to split too long sys_mq_timedsend */ static void __do_notify(struct mqueue_inode_info *info) { /* notification * invoked when there is registered process and there isn't process * waiting synchronously for message AND state of queue changed from * empty to not empty. Here we are sure that no one is waiting * synchronously. */ if (info->notify_owner && info->attr.mq_curmsgs == 1) { struct siginfo sig_i; switch (info->notify.sigev_notify) { case SIGEV_NONE: break; case SIGEV_SIGNAL: /* sends signal */ sig_i.si_signo = info->notify.sigev_signo; sig_i.si_errno = 0; sig_i.si_code = SI_MESGQ; sig_i.si_value = info->notify.sigev_value; /* map current pid/uid into info->owner's namespaces */ rcu_read_lock(); sig_i.si_pid = task_tgid_nr_ns(current, ns_of_pid(info->notify_owner)); sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid()); rcu_read_unlock(); kill_pid_info(info->notify.sigev_signo, &sig_i, info->notify_owner); break; case SIGEV_THREAD: set_cookie(info->notify_cookie, NOTIFY_WOKENUP); netlink_sendskb(info->notify_sock, info->notify_cookie); break; } /* after notification unregisters process */ put_pid(info->notify_owner); put_user_ns(info->notify_user_ns); info->notify_owner = NULL; info->notify_user_ns = NULL; } wake_up(&info->wait_q); } static int prepare_timeout(const struct timespec __user *u_abs_timeout, struct timespec64 *ts) { if (get_timespec64(ts, u_abs_timeout)) return -EFAULT; if (!timespec64_valid(ts)) return -EINVAL; return 0; } static void remove_notification(struct mqueue_inode_info *info) { if (info->notify_owner != NULL && info->notify.sigev_notify == SIGEV_THREAD) { set_cookie(info->notify_cookie, NOTIFY_REMOVED); netlink_sendskb(info->notify_sock, info->notify_cookie); } put_pid(info->notify_owner); put_user_ns(info->notify_user_ns); info->notify_owner = NULL; info->notify_user_ns = NULL; } static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr) { int mq_treesize; unsigned long total_size; if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0) return -EINVAL; if (capable(CAP_SYS_RESOURCE)) { if (attr->mq_maxmsg > HARD_MSGMAX || attr->mq_msgsize > HARD_MSGSIZEMAX) return -EINVAL; } else { if (attr->mq_maxmsg > ipc_ns->mq_msg_max || attr->mq_msgsize > ipc_ns->mq_msgsize_max) return -EINVAL; } /* check for overflow */ if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg) return -EOVERFLOW; mq_treesize = attr->mq_maxmsg * sizeof(struct msg_msg) + min_t(unsigned int, attr->mq_maxmsg, MQ_PRIO_MAX) * sizeof(struct posix_msg_tree_node); total_size = attr->mq_maxmsg * attr->mq_msgsize; if (total_size + mq_treesize < total_size) return -EOVERFLOW; return 0; } /* * Invoked when creating a new queue via sys_mq_open */ static struct file *do_create(struct ipc_namespace *ipc_ns, struct inode *dir, struct path *path, int oflag, umode_t mode, struct mq_attr *attr) { const struct cred *cred = current_cred(); int ret; if (attr) { ret = mq_attr_ok(ipc_ns, attr); if (ret) return ERR_PTR(ret); /* store for use during create */ path->dentry->d_fsdata = attr; } else { struct mq_attr def_attr; def_attr.mq_maxmsg = min(ipc_ns->mq_msg_max, ipc_ns->mq_msg_default); def_attr.mq_msgsize = min(ipc_ns->mq_msgsize_max, ipc_ns->mq_msgsize_default); ret = mq_attr_ok(ipc_ns, &def_attr); if (ret) return ERR_PTR(ret); } mode &= ~current_umask(); ret = vfs_create(dir, path->dentry, mode, true); path->dentry->d_fsdata = NULL; if (ret) return ERR_PTR(ret); return dentry_open(path, oflag, cred); } /* Opens existing queue */ static struct file *do_open(struct path *path, int oflag) { static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE, MAY_READ | MAY_WRITE }; int acc; if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) return ERR_PTR(-EINVAL); acc = oflag2acc[oflag & O_ACCMODE]; if (inode_permission(d_inode(path->dentry), acc)) return ERR_PTR(-EACCES); return dentry_open(path, oflag, current_cred()); } static int do_mq_open(const char __user *u_name, int oflag, umode_t mode, struct mq_attr *attr) { struct path path; struct file *filp; struct filename *name; int fd, error; struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; struct vfsmount *mnt = ipc_ns->mq_mnt; struct dentry *root = mnt->mnt_root; int ro; audit_mq_open(oflag, mode, attr); if (IS_ERR(name = getname(u_name))) return PTR_ERR(name); fd = get_unused_fd_flags(O_CLOEXEC); if (fd < 0) goto out_putname; ro = mnt_want_write(mnt); /* we'll drop it in any case */ error = 0; inode_lock(d_inode(root)); path.dentry = lookup_one_len(name->name, root, strlen(name->name)); if (IS_ERR(path.dentry)) { error = PTR_ERR(path.dentry); goto out_putfd; } path.mnt = mntget(mnt); if (oflag & O_CREAT) { if (d_really_is_positive(path.dentry)) { /* entry already exists */ audit_inode(name, path.dentry, 0); if (oflag & O_EXCL) { error = -EEXIST; goto out; } filp = do_open(&path, oflag); } else { if (ro) { error = ro; goto out; } audit_inode_parent_hidden(name, root); filp = do_create(ipc_ns, d_inode(root), &path, oflag, mode, attr); } } else { if (d_really_is_negative(path.dentry)) { error = -ENOENT; goto out; } audit_inode(name, path.dentry, 0); filp = do_open(&path, oflag); } if (!IS_ERR(filp)) fd_install(fd, filp); else error = PTR_ERR(filp); out: path_put(&path); out_putfd: if (error) { put_unused_fd(fd); fd = error; } inode_unlock(d_inode(root)); if (!ro) mnt_drop_write(mnt); out_putname: putname(name); return fd; } SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode, struct mq_attr __user *, u_attr) { struct mq_attr attr; if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr))) return -EFAULT; return do_mq_open(u_name, oflag, mode, u_attr ? &attr : NULL); } SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name) { int err; struct filename *name; struct dentry *dentry; struct inode *inode = NULL; struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns; struct vfsmount *mnt = ipc_ns->mq_mnt; name = getname(u_name); if (IS_ERR(name)) return PTR_ERR(name); audit_inode_parent_hidden(name, mnt->mnt_root); err = mnt_want_write(mnt); if (err) goto out_name; inode_lock_nested(d_inode(mnt->mnt_root), I_MUTEX_PARENT); dentry = lookup_one_len(name->name, mnt->mnt_root, strlen(name->name)); if (IS_ERR(dentry)) { err = PTR_ERR(dentry); goto out_unlock; } inode = d_inode(dentry); if (!inode) { err = -ENOENT; } else { ihold(inode); err = vfs_unlink(d_inode(dentry->d_parent), dentry, NULL); } dput(dentry); out_unlock: inode_unlock(d_inode(mnt->mnt_root)); if (inode) iput(inode); mnt_drop_write(mnt); out_name: putname(name); return err; } /* Pipelined send and receive functions. * * If a receiver finds no waiting message, then it registers itself in the * list of waiting receivers. A sender checks that list before adding the new * message into the message array. If there is a waiting receiver, then it * bypasses the message array and directly hands the message over to the * receiver. The receiver accepts the message and returns without grabbing the * queue spinlock: * * - Set pointer to message. * - Queue the receiver task for later wakeup (without the info->lock). * - Update its state to STATE_READY. Now the receiver can continue. * - Wake up the process after the lock is dropped. Should the process wake up * before this wakeup (due to a timeout or a signal) it will either see * STATE_READY and continue or acquire the lock to check the state again. * * The same algorithm is used for senders. */ /* pipelined_send() - send a message directly to the task waiting in * sys_mq_timedreceive() (without inserting message into a queue). */ static inline void pipelined_send(struct wake_q_head *wake_q, struct mqueue_inode_info *info, struct msg_msg *message, struct ext_wait_queue *receiver) { receiver->msg = message; list_del(&receiver->list); wake_q_add(wake_q, receiver->task); /* * Rely on the implicit cmpxchg barrier from wake_q_add such * that we can ensure that updating receiver->state is the last * write operation: As once set, the receiver can continue, * and if we don't have the reference count from the wake_q, * yet, at that point we can later have a use-after-free * condition and bogus wakeup. */ receiver->state = STATE_READY; } /* pipelined_receive() - if there is task waiting in sys_mq_timedsend() * gets its message and put to the queue (we have one free place for sure). */ static inline void pipelined_receive(struct wake_q_head *wake_q, struct mqueue_inode_info *info) { struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND); if (!sender) { /* for poll */ wake_up_interruptible(&info->wait_q); return; } if (msg_insert(sender->msg, info)) return; list_del(&sender->list); wake_q_add(wake_q, sender->task); sender->state = STATE_READY; } static int do_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr, size_t msg_len, unsigned int msg_prio, struct timespec64 *ts) { struct fd f; struct inode *inode; struct ext_wait_queue wait; struct ext_wait_queue *receiver; struct msg_msg *msg_ptr; struct mqueue_inode_info *info; ktime_t expires, *timeout = NULL; struct posix_msg_tree_node *new_leaf = NULL; int ret = 0; DEFINE_WAKE_Q(wake_q); if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX)) return -EINVAL; if (ts) { expires = timespec64_to_ktime(*ts); timeout = &expires; } audit_mq_sendrecv(mqdes, msg_len, msg_prio, ts); f = fdget(mqdes); if (unlikely(!f.file)) { ret = -EBADF; goto out; } inode = file_inode(f.file); if (unlikely(f.file->f_op != &mqueue_file_operations)) { ret = -EBADF; goto out_fput; } info = MQUEUE_I(inode); audit_file(f.file); if (unlikely(!(f.file->f_mode & FMODE_WRITE))) { ret = -EBADF; goto out_fput; } if (unlikely(msg_len > info->attr.mq_msgsize)) { ret = -EMSGSIZE; goto out_fput; } /* First try to allocate memory, before doing anything with * existing queues. */ msg_ptr = load_msg(u_msg_ptr, msg_len); if (IS_ERR(msg_ptr)) { ret = PTR_ERR(msg_ptr); goto out_fput; } msg_ptr->m_ts = msg_len; msg_ptr->m_type = msg_prio; /* * msg_insert really wants us to have a valid, spare node struct so * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will * fall back to that if necessary. */ if (!info->node_cache) new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL); spin_lock(&info->lock); if (!info->node_cache && new_leaf) { /* Save our speculative allocation into the cache */ INIT_LIST_HEAD(&new_leaf->msg_list); info->node_cache = new_leaf; new_leaf = NULL; } else { kfree(new_leaf); } if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) { if (f.file->f_flags & O_NONBLOCK) { ret = -EAGAIN; } else { wait.task = current; wait.msg = (void *) msg_ptr; wait.state = STATE_NONE; ret = wq_sleep(info, SEND, timeout, &wait); /* * wq_sleep must be called with info->lock held, and * returns with the lock released */ goto out_free; } } else { receiver = wq_get_first_waiter(info, RECV); if (receiver) { pipelined_send(&wake_q, info, msg_ptr, receiver); } else { /* adds message to the queue */ ret = msg_insert(msg_ptr, info); if (ret) goto out_unlock; __do_notify(info); } inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); } out_unlock: spin_unlock(&info->lock); wake_up_q(&wake_q); out_free: if (ret) free_msg(msg_ptr); out_fput: fdput(f); out: return ret; } static int do_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr, size_t msg_len, unsigned int __user *u_msg_prio, struct timespec64 *ts) { ssize_t ret; struct msg_msg *msg_ptr; struct fd f; struct inode *inode; struct mqueue_inode_info *info; struct ext_wait_queue wait; ktime_t expires, *timeout = NULL; struct posix_msg_tree_node *new_leaf = NULL; if (ts) { expires = timespec64_to_ktime(*ts); timeout = &expires; } audit_mq_sendrecv(mqdes, msg_len, 0, ts); f = fdget(mqdes); if (unlikely(!f.file)) { ret = -EBADF; goto out; } inode = file_inode(f.file); if (unlikely(f.file->f_op != &mqueue_file_operations)) { ret = -EBADF; goto out_fput; } info = MQUEUE_I(inode); audit_file(f.file); if (unlikely(!(f.file->f_mode & FMODE_READ))) { ret = -EBADF; goto out_fput; } /* checks if buffer is big enough */ if (unlikely(msg_len < info->attr.mq_msgsize)) { ret = -EMSGSIZE; goto out_fput; } /* * msg_insert really wants us to have a valid, spare node struct so * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will * fall back to that if necessary. */ if (!info->node_cache) new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL); spin_lock(&info->lock); if (!info->node_cache && new_leaf) { /* Save our speculative allocation into the cache */ INIT_LIST_HEAD(&new_leaf->msg_list); info->node_cache = new_leaf; } else { kfree(new_leaf); } if (info->attr.mq_curmsgs == 0) { if (f.file->f_flags & O_NONBLOCK) { spin_unlock(&info->lock); ret = -EAGAIN; } else { wait.task = current; wait.state = STATE_NONE; ret = wq_sleep(info, RECV, timeout, &wait); msg_ptr = wait.msg; } } else { DEFINE_WAKE_Q(wake_q); msg_ptr = msg_get(info); inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); /* There is now free space in queue. */ pipelined_receive(&wake_q, info); spin_unlock(&info->lock); wake_up_q(&wake_q); ret = 0; } if (ret == 0) { ret = msg_ptr->m_ts; if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) || store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) { ret = -EFAULT; } free_msg(msg_ptr); } out_fput: fdput(f); out: return ret; } SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr, size_t, msg_len, unsigned int, msg_prio, const struct timespec __user *, u_abs_timeout) { struct timespec64 ts, *p = NULL; if (u_abs_timeout) { int res = prepare_timeout(u_abs_timeout, &ts); if (res) return res; p = &ts; } return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p); } SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr, size_t, msg_len, unsigned int __user *, u_msg_prio, const struct timespec __user *, u_abs_timeout) { struct timespec64 ts, *p = NULL; if (u_abs_timeout) { int res = prepare_timeout(u_abs_timeout, &ts); if (res) return res; p = &ts; } return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p); } /* * Notes: the case when user wants us to deregister (with NULL as pointer) * and he isn't currently owner of notification, will be silently discarded. * It isn't explicitly defined in the POSIX. */ static int do_mq_notify(mqd_t mqdes, const struct sigevent *notification) { int ret; struct fd f; struct sock *sock; struct inode *inode; struct mqueue_inode_info *info; struct sk_buff *nc; audit_mq_notify(mqdes, notification); nc = NULL; sock = NULL; if (notification != NULL) { if (unlikely(notification->sigev_notify != SIGEV_NONE && notification->sigev_notify != SIGEV_SIGNAL && notification->sigev_notify != SIGEV_THREAD)) return -EINVAL; if (notification->sigev_notify == SIGEV_SIGNAL && !valid_signal(notification->sigev_signo)) { return -EINVAL; } if (notification->sigev_notify == SIGEV_THREAD) { long timeo; /* create the notify skb */ nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL); if (!nc) { ret = -ENOMEM; goto out; } if (copy_from_user(nc->data, notification->sigev_value.sival_ptr, NOTIFY_COOKIE_LEN)) { ret = -EFAULT; goto out; } /* TODO: add a header? */ skb_put(nc, NOTIFY_COOKIE_LEN); /* and attach it to the socket */ retry: f = fdget(notification->sigev_signo); if (!f.file) { ret = -EBADF; goto out; } sock = netlink_getsockbyfilp(f.file); fdput(f); if (IS_ERR(sock)) { ret = PTR_ERR(sock); sock = NULL; goto out; } timeo = MAX_SCHEDULE_TIMEOUT; ret = netlink_attachskb(sock, nc, &timeo, NULL); if (ret == 1) { sock = NULL; goto retry; } if (ret) { sock = NULL; nc = NULL; goto out; } } } f = fdget(mqdes); if (!f.file) { ret = -EBADF; goto out; } inode = file_inode(f.file); if (unlikely(f.file->f_op != &mqueue_file_operations)) { ret = -EBADF; goto out_fput; } info = MQUEUE_I(inode); ret = 0; spin_lock(&info->lock); if (notification == NULL) { if (info->notify_owner == task_tgid(current)) { remove_notification(info); inode->i_atime = inode->i_ctime = current_time(inode); } } else if (info->notify_owner != NULL) { ret = -EBUSY; } else { switch (notification->sigev_notify) { case SIGEV_NONE: info->notify.sigev_notify = SIGEV_NONE; break; case SIGEV_THREAD: info->notify_sock = sock; info->notify_cookie = nc; sock = NULL; nc = NULL; info->notify.sigev_notify = SIGEV_THREAD; break; case SIGEV_SIGNAL: info->notify.sigev_signo = notification->sigev_signo; info->notify.sigev_value = notification->sigev_value; info->notify.sigev_notify = SIGEV_SIGNAL; break; } info->notify_owner = get_pid(task_tgid(current)); info->notify_user_ns = get_user_ns(current_user_ns()); inode->i_atime = inode->i_ctime = current_time(inode); } spin_unlock(&info->lock); out_fput: fdput(f); out: if (sock) netlink_detachskb(sock, nc); else if (nc) dev_kfree_skb(nc); return ret; } SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes, const struct sigevent __user *, u_notification) { struct sigevent n, *p = NULL; if (u_notification) { if (copy_from_user(&n, u_notification, sizeof(struct sigevent))) return -EFAULT; p = &n; } return do_mq_notify(mqdes, p); } static int do_mq_getsetattr(int mqdes, struct mq_attr *new, struct mq_attr *old) { struct fd f; struct inode *inode; struct mqueue_inode_info *info; if (new && (new->mq_flags & (~O_NONBLOCK))) return -EINVAL; f = fdget(mqdes); if (!f.file) return -EBADF; if (unlikely(f.file->f_op != &mqueue_file_operations)) { fdput(f); return -EBADF; } inode = file_inode(f.file); info = MQUEUE_I(inode); spin_lock(&info->lock); if (old) { *old = info->attr; old->mq_flags = f.file->f_flags & O_NONBLOCK; } if (new) { audit_mq_getsetattr(mqdes, new); spin_lock(&f.file->f_lock); if (new->mq_flags & O_NONBLOCK) f.file->f_flags |= O_NONBLOCK; else f.file->f_flags &= ~O_NONBLOCK; spin_unlock(&f.file->f_lock); inode->i_atime = inode->i_ctime = current_time(inode); } spin_unlock(&info->lock); fdput(f); return 0; } SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes, const struct mq_attr __user *, u_mqstat, struct mq_attr __user *, u_omqstat) { int ret; struct mq_attr mqstat, omqstat; struct mq_attr *new = NULL, *old = NULL; if (u_mqstat) { new = &mqstat; if (copy_from_user(new, u_mqstat, sizeof(struct mq_attr))) return -EFAULT; } if (u_omqstat) old = &omqstat; ret = do_mq_getsetattr(mqdes, new, old); if (ret || !old) return ret; if (copy_to_user(u_omqstat, old, sizeof(struct mq_attr))) return -EFAULT; return 0; } #ifdef CONFIG_COMPAT struct compat_mq_attr { compat_long_t mq_flags; /* message queue flags */ compat_long_t mq_maxmsg; /* maximum number of messages */ compat_long_t mq_msgsize; /* maximum message size */ compat_long_t mq_curmsgs; /* number of messages currently queued */ compat_long_t __reserved[4]; /* ignored for input, zeroed for output */ }; static inline int get_compat_mq_attr(struct mq_attr *attr, const struct compat_mq_attr __user *uattr) { struct compat_mq_attr v; if (copy_from_user(&v, uattr, sizeof(*uattr))) return -EFAULT; memset(attr, 0, sizeof(*attr)); attr->mq_flags = v.mq_flags; attr->mq_maxmsg = v.mq_maxmsg; attr->mq_msgsize = v.mq_msgsize; attr->mq_curmsgs = v.mq_curmsgs; return 0; } static inline int put_compat_mq_attr(const struct mq_attr *attr, struct compat_mq_attr __user *uattr) { struct compat_mq_attr v; memset(&v, 0, sizeof(v)); v.mq_flags = attr->mq_flags; v.mq_maxmsg = attr->mq_maxmsg; v.mq_msgsize = attr->mq_msgsize; v.mq_curmsgs = attr->mq_curmsgs; if (copy_to_user(uattr, &v, sizeof(*uattr))) return -EFAULT; return 0; } COMPAT_SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, compat_mode_t, mode, struct compat_mq_attr __user *, u_attr) { struct mq_attr attr, *p = NULL; if (u_attr && oflag & O_CREAT) { p = &attr; if (get_compat_mq_attr(&attr, u_attr)) return -EFAULT; } return do_mq_open(u_name, oflag, mode, p); } static int compat_prepare_timeout(const struct compat_timespec __user *p, struct timespec64 *ts) { if (compat_get_timespec64(ts, p)) return -EFAULT; if (!timespec64_valid(ts)) return -EINVAL; return 0; } COMPAT_SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr, compat_size_t, msg_len, unsigned int, msg_prio, const struct compat_timespec __user *, u_abs_timeout) { struct timespec64 ts, *p = NULL; if (u_abs_timeout) { int res = compat_prepare_timeout(u_abs_timeout, &ts); if (res) return res; p = &ts; } return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p); } COMPAT_SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr, compat_size_t, msg_len, unsigned int __user *, u_msg_prio, const struct compat_timespec __user *, u_abs_timeout) { struct timespec64 ts, *p = NULL; if (u_abs_timeout) { int res = compat_prepare_timeout(u_abs_timeout, &ts); if (res) return res; p = &ts; } return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p); } COMPAT_SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes, const struct compat_sigevent __user *, u_notification) { struct sigevent n, *p = NULL; if (u_notification) { if (get_compat_sigevent(&n, u_notification)) return -EFAULT; if (n.sigev_notify == SIGEV_THREAD) n.sigev_value.sival_ptr = compat_ptr(n.sigev_value.sival_int); p = &n; } return do_mq_notify(mqdes, p); } COMPAT_SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes, const struct compat_mq_attr __user *, u_mqstat, struct compat_mq_attr __user *, u_omqstat) { int ret; struct mq_attr mqstat, omqstat; struct mq_attr *new = NULL, *old = NULL; if (u_mqstat) { new = &mqstat; if (get_compat_mq_attr(new, u_mqstat)) return -EFAULT; } if (u_omqstat) old = &omqstat; ret = do_mq_getsetattr(mqdes, new, old); if (ret || !old) return ret; if (put_compat_mq_attr(old, u_omqstat)) return -EFAULT; return 0; } #endif static const struct inode_operations mqueue_dir_inode_operations = { .lookup = simple_lookup, .create = mqueue_create, .unlink = mqueue_unlink, }; static const struct file_operations mqueue_file_operations = { .flush = mqueue_flush_file, .poll = mqueue_poll_file, .read = mqueue_read_file, .llseek = default_llseek, }; static const struct super_operations mqueue_super_ops = { .alloc_inode = mqueue_alloc_inode, .destroy_inode = mqueue_destroy_inode, .evict_inode = mqueue_evict_inode, .statfs = simple_statfs, }; static struct file_system_type mqueue_fs_type = { .name = "mqueue", .mount = mqueue_mount, .kill_sb = kill_litter_super, .fs_flags = FS_USERNS_MOUNT, }; int mq_init_ns(struct ipc_namespace *ns) { ns->mq_queues_count = 0; ns->mq_queues_max = DFLT_QUEUESMAX; ns->mq_msg_max = DFLT_MSGMAX; ns->mq_msgsize_max = DFLT_MSGSIZEMAX; ns->mq_msg_default = DFLT_MSG; ns->mq_msgsize_default = DFLT_MSGSIZE; ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns); if (IS_ERR(ns->mq_mnt)) { int err = PTR_ERR(ns->mq_mnt); ns->mq_mnt = NULL; return err; } return 0; } void mq_clear_sbinfo(struct ipc_namespace *ns) { ns->mq_mnt->mnt_sb->s_fs_info = NULL; } void mq_put_mnt(struct ipc_namespace *ns) { kern_unmount(ns->mq_mnt); } static int __init init_mqueue_fs(void) { int error; mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache", sizeof(struct mqueue_inode_info), 0, SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT, init_once); if (mqueue_inode_cachep == NULL) return -ENOMEM; /* ignore failures - they are not fatal */ mq_sysctl_table = mq_register_sysctl_table(); error = register_filesystem(&mqueue_fs_type); if (error) goto out_sysctl; spin_lock_init(&mq_lock); error = mq_init_ns(&init_ipc_ns); if (error) goto out_filesystem; return 0; out_filesystem: unregister_filesystem(&mqueue_fs_type); out_sysctl: if (mq_sysctl_table) unregister_sysctl_table(mq_sysctl_table); kmem_cache_destroy(mqueue_inode_cachep); return error; } device_initcall(init_mqueue_fs);